The present invention relates to an apparatus for forming a film by depositing particles produced by a cathode sputtering on an object to be coated.
FIG. 4 is a section showing a film forming apparatus according to the prior art. In FIG. 4, reference numeral 7 designates a vacuum chamber, numeral 9 designates a cylindrical anode disposed in the vacuum chamber 7, and numeral 4 designates an anode lead connected with a not-shown DC high-voltage power source. Numeral 5 designates an insulator for fixing the anode lead 4 in the vacuum chamber 7. Numerals 10a and 10b designate a pair of opposed cathodes which are disposed at the two sides of the anode 9. The opposed cathodes 10a and 10b have their faces directed at a right angle with respect to the cylindrical center line of the anode 9. Numeral 11 designates a circular passage hole which is formed in the cathode 10a. The passage hole 11 is positioned in the vicinity of that portion of the cathode 10a, which faces the end face of the anode 9. Numeral 12 designates a conduit which has its one end communicating with the inside of the vacuum chamber 7 and its center line aligned with that of the passage hole 11. At one end of the conduit 12, there is supported a holed plate 18 having a hole 19. This holed plate 18 is generally flush with the end portion of the conduit 12. Numerals 8a and 8b designate magnets which are mounted on the vacuum chamber 7. The magnet 8a is formed with a hole through which extends the conduit 12. Numeral 15 designates a vacuum sealing member which is fitted in the end portion of the conduit 12. Numeral 16 designates an exhaust pipe which is attached to the vacuum chamber 7 and connected to a not-shown evacuation apparatus. Numeral 17 designates an introduction pipe which is attached like the exhaust pipe to the vacuum chamber 7 and connected to a not-shown inert gas introduction apparatus. In the film forming apparatus thus constructed, an object 6 to be coated is held in abutment against the sealing member 15. After this, the vacuum chamber 7 is evacuated by the evacuation apparatus, and inert gases such as argon gases are introduced into the vacuum chamber 7 by the inert gas introduction apparatus to establish an inert gas atmosphere under a vacuum of 1.times.10.sup.-2 Pa or higher in the vacuum chamber 7. After this, a high voltage is applied between the anode 9 and the cathodes 10a and 10b to cause a cold cathode discharge between the anode 9 and the cathodes 10a and 10b so that the argon atoms in the discharge space may be ionized. The positive argon ions thus produced bombard the surfaces of the cathodes 10a and 10b to sputter the substance making the cathodes 10a and 10b. Moreover, the metal particles and charged particles produced by the surface sputtering pass through the passage hole 11 and the conduit 12 until they deposit on the object 6 arranged at the end portion of the conduit 12, thus forming a film on the object outside of the vacuum chamber.